Python - sorted list

Question

If I got this line of code:

my_list = [3,4,7,2,1,6,8,2,1,4]

I can sort this list with:

my_list.sort()

But if I want to create a product list, For example: 2 milks, 3 cookies and so on, if I will sort this list [3,2] I will not be able to know how many milk should I buy or cookies. My question is how can I use dictionary or list so I would be able to sort the list/dictionary and also know the product name after the sort.

score 3 · Answer 1 · answered May 21 '17 at 18:05

3

Put the values in tuples and they will stay together.

>>> L = [(3, 'cookies'), (2, 'milk')]
>>> L
[(3, 'cookies'), (2, 'milk')]
>>> L.sort()
>>> L
[(2, 'milk'), (3, 'cookies')]

The number must come first as when tuples are compared, first the first element is compared, then the second, etc. This is called lexicographical order.

answered May 21 '17 at 18:05

Alex Hall

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Is there any limit for the tuple length for sorting? Just curious. – Prajwal May 21 '17 at 18:09
1

@Prajwal nah, as long as the tuple can stay in memory. – Alex Hall May 21 '17 at 18:10

score 3 · Accepted Answer · answered May 21 '17 at 18:07

Well it depends on how you represent your product list. Say however we represent it as a list of tupes:

product_list = [(2,'milk'),(3,'cookie')]

Now you can sort with a key and set reverse on True to sort in descending order:

product_list.sort(reverse=True, key=lambda x: x[0])

So now we sort on the first item of each tuple and we do it in descending order. This will result in:

>>> product_list
[(3, 'cookie'), (2, 'milk')]

Python - sorted list

2 Answers2